public class Test {
}

class X{
    Y y=new Y();//1
    public X(){//2
        System.out.print("X");
    }
}
class Y{
    public Y(){//3
        System.out.print("Y");
    }
}
class Z extends X{
    Y y=new Y();//4
    public Z(){//5
        System.out.print("Z");
    }
    public static void main(String[] args) {
        new Z();
    }
}

class Base1 {
    Base1() {
        System.out.print("Base");
    }
}

class Alpha extends Base1 {

    public static void main( String[] args ) {
        new Alpha();//1
        //调用父类无参的构造方法
        new Base1();//2
    }
}
